Prior art silicone defoaming agents have various properties, such as a high defoaming effect on aqueous and nonaqueous foaming materials, even when added in small amounts and chemical inertness and they are colorless, transparent and odorless and do not adversely affect the pharmaceutical or chemical product. As a result, they are widely used for defoaming and foam inhibition.
A poly(dimethylsiloxane) oil, as such, or a compound-type defoaming agent comprising fine powdery silica dispersed in poly(dimethylsiloxane) oil, is generally used for defoaming or foam inhibition in nonaqueous systems based on the above properties. An emulsion-type defoaming agent, in which the above-mentioned compound is emulsified with an appropriate emulsifier or emulsification assistant, is used for defoaming or foam inhibition in aqueous systems. In addition, powdery defoaming agents have been proposed in which the compound or poly(dimethyliloxane) oil mentioned above is taken up into calcium carbonate, magnesium carbonate, cork powder, etc. (Japanese Patent No. 40-1367 [No.65-1367] and Japanese Kokai Patents No. 51-20787 [No. 76-20787] and 57-171405 [No. 82-171405]).
The emulsion types, which are applied in aqueous systems, suffer from the following drawbacks. (1) The ability of the emulsion deteriorates due to changes in temperature, due to vibrations during transport as well as due simply to long-term storage with the result that the emulsion system is broken. (2) They are subject to spoilage and mildew, unless combined with the appropriate preservative or antimold. (3) They require a device such as a measuring pump, or require manual labor when added to the foaming system. The prior art powdery defoaming agents exhibit the following drawbacks in practical application. (4) The oil exudes with time and (5) manual labor is required for addition to the foaming system.
The present invention describes a solid silicone defoaming agent which does not suffer from the above-described drawbacks and the present invention also describes a method for producing said solid silicone defoaming agent.
With the installation of the solid silicone defoaming agent of the present invention, human intervention is not required for at least several days and the immediate and long-term effects are excellent.
In addition, the method of the present invention reliably produces a solid silicone defoaming agent which does not bleed while having the excellent properties mentioned above.
The solid silicone defoaming agent of the present invention is extremely useful for defoaming such foaming systems as septic tanks and sewage.